The astronauts asked to repair a loose thermal blanket on shuttle Atlantis have studied the fine points of aerospace engineering and built their strength for the strenuous task in weight rooms.

The actual repair job may involve a skill they learned way back in their high school home economics classes — sewing.

NASA managers said Tuesday they are leaning toward having the astronauts repair the thermal blanket using stainless steel wire and an instrument with a rounded end that resembles a small needle.

No final decision has been made on when the repair will be made, or what repair technique will be used. Engineers also have looked at using wire ties and adhesives to secure the blanket. They are testing the different methods in heat and wind tunnel tests.

The shuttle astronauts’ 11-day mission was extended by two days to allow time to fix the thermal blanket, which peeled up during launch last week.

The 4-by-6-inch damaged section sits over an engine pod and will be repaired during either the mission’s third spacewalk on Friday or the fourth spacewalk on Sunday.

An investigation has started into how the blanket was secured before launch. Such blankets are used to protect the shuttle from searing heat during re-entry.

Engineers don’t think the intense heat could burn through the graphite structure under the blanket and jeopardize the spacecraft, but it could damage the shuttle and require schedule-busting repairs.

“This is just the right thing to do, the prudent thing to do,” said Atlantis commander Rick Sturckow.

NASA has been cautious about any potential damage to the wing leading edge since the Columbia disaster in 2003 killed seven astronauts. Foam fell off Columbia’s external fuel tank during launch and punctured the wing, allowing fiery gases to penetrate it during re-entry.

While NASA figures out how to do the repairs, two astronauts were expected Wednesday to go on the second spacewalk of Atlantis’ mission to the international space station.

Before astronauts Patrick Forrester and Steve Swanson float outside the space station, Mission Control in Houston planned to send commands to begin folding up a 115-foot solar wing.

NASA struggled to fold up its twin array during a shuttle mission last December when guidewires got stuck on grommets along the way. So the space agency has taken precautions in anticipation of the retraction going less than smoothly.

The array’s 31 sections will be folded up one at a time, and, if needed, the spacewalking astronauts will be asked to use specially-designed tools to push on the panels to fold them correctly.

The old array needs to be folded up so that a new pair of solar arrays delivered by Atlantis this week can follow the sun, generating enough power for 10 households. The new pair of arrays unfolded like an accordion window blind by remote commands from Mission Control on Tuesday.

On the Net:

Shuttle mission: http://www.nasa.gov/mission—pages/shuttle/main/index.html